Soil Solution Cl -

1. Main Cycle More Info Links Cl- cycling in soils Plant and Animal residues Atmospheric Cl- Plant Uptake Primary and Secondary Cl minerals Soil Organic matter Soil Solution Cl- Dissolution Precipitation Mineralization Immobilization Adsorption Adsorbed or labile Cl- Desorption Leaching

2. Main Cycle More Info Cl- cycling in soils Plant and Animal residues Atmospheric Cl- Plant Uptake Primary and Secondary Cl minerals Soil Organic matter Soil Solution Cl- Dissolution Precipitation Mineralization Immobilization Adsorption Adsorbed or labile Cl- Desorption Leaching

3. Main Cycle More Info Cl- cycling in soils Plant and Animal residues Atmospheric Cl- Plant Uptake Primary and Secondary Cl minerals Soil Organic matter Soil Solution Cl- Dissolution Precipitation Mineralization Immobilization Adsorption Adsorbed or labile Cl- Desorption Leaching

4. Main Cycle More Info Cl- cycling in soils Plant and Animal residues Atmospheric Cl- Plant Uptake Primary and Secondary Cl minerals Soil Organic matter Soil Solution Cl- Dissolution Precipitation Mineralization Immobilization Adsorption Adsorbed or labile Cl- Desorption Leaching

5. Main Cycle More Info Cl- cycling in soils Plant and Animal residues Atmospheric Cl- Plant Uptake Primary and Secondary Cl minerals Soil Organic matter Soil Solution Cl- Dissolution Precipitation Mineralization Immobilization Adsorption Adsorbed or labile Cl- Desorption Leaching

6. More Information on Chloride Form taken up by plants: Deficiency symptoms: Mobility in soil: Effect of pH on availability: Mobility in plant: Origins of Cl in soil and plants: Role of nutrient in plant growth: Fertilizer Sources: Behavior in soil: Role in microbial growth: Accumulations of Cl in soil: Interactions of Cl: Effects: Concentration in plants: Other: Forms in soil: Toxicity Symptoms: Main Cycle References:

7. More Info. on Chloride • Form taken up by plants Cl- • Mobility in Soil Mobile • Mobility in plant Mobile • Effect of pH on availability: Non adsorbed at pH >7   Non specific adsorption pH <7   No effect on availability Main Cycle More Info

8. More Info. on Chloride • Role of nutrient in plant growth: Stimulates splitting of water in photosynthesis, essential for roots, cell division in leaves and as an osmotically active solute. Winter Wheat: Suppresses take-all, stripe rust, tan spot.   Wheat: Suppresses leaf rust and tan spot. Oats: Suppresses leaf rust Corn: Suppresses stalk rot • Role in microbial growth: Unknown Main Cycle More Info

9. More Info. on Chloride • Interactions with other nutrients: Uptake of NO3 and SO4 can be reduced by the competitive effects of Cl. Lower protein concentrations in winter wheat are attributed to strong competitive relationships between Cl and NO3 when Cl levels are high. Negative interaction between Cl and NO3 has been attributed to competition for carrier sites at root surfaces. • Fertilizer Sources: Source %Cl Ammonium Chloride 66 Calcium Chloride 65 Potassium Chloride 47 Magnesium Chloride 74 Sodium Chloride 60 Main Cycle More Info

10. More Info. on Chloride • Concentration in plants: Normal concentration is 0.2 - 2.0 % of dry matter. Cereal grain concentrations are 10-20 ppm, sugarbeet leaves 100-200 ppm. Tobacco plants require concentrations in soil of 10-15 ppm. <70-700 ug/g in tissue is deficient. • Deficiency symptoms: pH unknown. Reduced growth, wilting, development of necrotic and chlorotic spots on leaves, with leaves eventually attaining a bronze color. Roots become stunted in length but thickened or club shaped near the tips. Acts as a counter ion during rapid K+ fluxes, contributes to turgor of leaves. Deficiency occurs in soils, <2ppm. Main Cycle More Info

11. More Info. on Chloride • Behavior in Soil Cl anion is very soluble in most soils. It is rapidly cycled through soil systems due to mobility (except in extremely acid soils). Exchangeable Cl can occur in acid, kaolinitic soils which have pH dependent positive charges. In humid climate zones Cl is leached through the soil system and in Arid to Semi-arid zones it is concentrated in the soil horizon. • Origins of Cl in Soil and Plants: Most Cl in soil comes from salt trapped in parent material, marine aerosols, and volcanic emissions. Most often found in apatite, hornblende, and some feldspars. Nearly all soil Cl has been in the oceans at least once and returned to land by uplift and subsequent leaching of marine sediments or by oceanic salt spray carried in rain or snow. Sea spray near coastal regions provides about 100 kg/ha/yr and for inland regions accumulations are 1-2 kg/ha/yr. For inland regions these amounts are adequate since no deficiencies have been reported. Salt droplets and dust particles can be absorbed by plant leaves in adequate amounts for plant requirements. Main Cycle More Info

12. More Info. on Chloride • Accumulations of Cl in soils: Accumulates where internal drainage of soils is restricted and in shallow groundwater where Cl can move by capillary action into the root zone and be deposited at or near the soil surface. • Effects: Primary effect is an increase of osmotic pressure of soil water and thereby lowers the availability of water to plants. • Forms in Soil: Most Cl exists as soluble salts of NaCl, CaCl2, or MgCl2. Main Cycle More Info

13. More Info. on Chloride • Toxicity Symptoms: pH unknown. Can reduce yield and quality of crops. High levels will increase total leaf water potential and cell sap osmotic potential in wheat. Improves moisture relations in some crops. Leaves of tobacco and potatoes become thickened and tend to roll when excessive Cl concentrations occur. Storage quality of potato tubers are adversely affected by surplus uptake of Cl. • Other: In recent years water softening, industrial brines, and road deicing have contributed significant amounts of Cl to local areas. Irrigation water that is highly mineralized, salt water spills associated with extraction of oil, natural gas, some coal deposits and improper disposal of feedlot wastes can supply Cl to soil. Wind erosion of salt evaporates can also affect enrichment of soils. Main Cycle More Info

14. References Bohn, H.L., B.L. McNeal and G.A. O’Connor. 1979. Soil Chemistry, Wiley-Interscience, New York, 219, 232, 286 pp. Pendias-Kabata, Alina and Henryk Pendias. 1992. Trace Elements in Soils and Plants. 2nd ed. CRC Press, Florida, 251-252pp. Salisbury, Frank B. and Cleon W. Ross. 1992. Plant Physiology, 4th ed. Wadsworth Inc., California, 120, 129, 133, 135, 148, 215, 217 pp. Tisdale, S.L., W.L. Nelson, J.D. Beaton and J.L. Havlin. 1993. Soil Fertility and Fertilizers. 5th ed. Macmillan, New York, 73-75, 342-344 pp. Authors: David Gay, Justin Carpenter, Mark Wood, Curt Woolfolk and J. Clemn Turner Main Cycle More Info

15. Links Chloride Crop Nutrition Nutrient Cycles **A Great Resource** Main Cycle More Info

16. Chlorine Cycle CH3 Cl Air pollution CFC’s Atmosphere Biomass Burning HCl HCl Ocean (Sea Spray) Dry fallout Cl2 Volcanic emissions HClO Precipitation Plants coast 100 kg/ha/yr inland 1-2 kg/ha/yr Road salts, Feedlots, Irrigation water Industrial wastewater Cl- Wind erosion of salt evaporates Soil NaCl MgCl2 CaCl2 Municipal water (Drinking + Swimming) Parent material Negligible addition Fertilizers KCl 0-0-62 47% Cl- Plastics (PVC-polyvinyl chloride) AEC only in acid soils Runoff 8 kg/ha/hr Leaching Cl- cycling in soils Atmospheric

17. Soils Air Pollution CFC’s Chlorine Cycle Ocean (sea spray) Biomass Burning Atmosphere Precipitation Volcanic Emissions Plants Cl- Road Salts, Feedlots, Irrigation Water, Industrial Wastewater Wind Erosion of Salt Evaporates Soil NaCl MgCl2 CaCl2 Municipal Water Parent Material Runoff Leaching Plastics Fertilizers